Top feed mechanism for overedge sewing machine

ABSTRACT

This disclosure relates to a top feed mechanism for an overedge sewing machine in which a top feed dog is articulately mounted upon a top feed bar to which feed and lift motions are transmitted by eccentrics. The top feed dog is carried by a pivotally mounted arm which is in turn connected to a slidably mounted rod above and generally in the plane of the top feed bar. Biasing means normally urge the rod in a direction tending to move the feed dog toward its fabric engaging position. Cam means carried by a rotatable plate are provided for moving the rod against the biasing force of the spring to pivot the arm and the feed dog carried thereby to an out-of-the-way position. Lifting motion is imparted to the top feed bar and a main feed bar by eccentrics which are generally 180* out of phase whereby the feed dogs move toward each other to grip fabric therebetween during the feed cycle and move away from each other to release fabric incident to the return cycle of the mechanism.

United States Patent 1 3, 36,899

Crisler [4 1 Jan. 25, 1972 TOP FEED MECHANISM FOR PrimaryExaminer-Richard .I. Scanlan,.lr.

OVEREDGE SEWING MACHINE AllomeyDiller, Brown, Ramik & Holt [72]Inventor: Larry Dean Crisler, Philadelphia, Pa. [57] ABSTRACT AssigneeiUnion Special Machine C mpa y, This disclosure relates to a top feedmechanism for an C c g overedge sewing machine in which atop feed dog isarticulate- [22] Filed: Man 6, 1970 ly mounted upon a top feed bar towhich feed and lift motions are transmltted by eccentrics. The top feeddog rs carried by a [21] Appl. No.: 17,088 pivotally mounted arm whichis in turn connected to n slidably mounted rod above and generally inthe plane of the top feed bar. Biasing means normally urge the rod in adirection tend- U.S. C1 g to move the feed dog toward its fabricengaging posmon Field of Search 2 162 213 Cam means carried by arotatable plate are provided for moving the rod against the biasingforce of the spring to pivot the arm and the feed dog carried thereby toan out-of-the-way [56] References cued position. Lifting motion isimparted to the top feed bar and a UNITED STATES PATENTS main feed barby eccentrics which are generally 180 out of phase whereby the feed dogsmove toward each other to grip 3,530,809 9/1970 Porter ..112/207 fabrictherebetween during the feed cycle and move away 2, 2 3/1958 ing u fromeach other to release fabric incident to the return cycle 1,995,9453/1935 Rube] et a1 ..1 12/207 of the mechanism.

3,256,844 6/1966 Chezaud et a1. ..112/207 18 Claims, 7 Drawing FiguresPATENTEU JAN25 m2 SHEET 1 OF 3 INVENTUR 1 1m LRRRY D. CRlSLER w wwmATTORNEYS Pmwmmsmz 3536.899

SHEET 2 OF 3 INVENTUR LQRPY D. CRISLER B %Z/ *hw 6' I Q YTD RNEYSPATENTEUJAH251972 SHEET 3 BF 3 \NVENTDR LQRRY D. CRBLER CKL, m r 'muwsTOP FEED MECHANISM FOR OVEREDGE SEWING MACHINE Many years ago it wasfound that conventional feed dogs which operated only on the undersideof fabric were inadequate when it became necessary to feed an upperlayer of fabric in exact synchronism with a lower layer in order tomaintain the layers in fixed relationship to each other during a sewingoperation. Top feed mechanisms of various types were thereforecontinuously developed to produce simultaneous synchronous movement oftop and main feed dogs so that multiply fabric workpieces could be fedtogether in the absence of slippage during a sewing operation. One suchmechanism is disclosed in commonly assigned U.S. Pat. No. 1,995,945 inthe name of Charles F. Rubel et al., issued Mar. 26, I935. Of course,since the issue of the latter-noted patent, more sophisticatedmechanisms have been designed and the following disclosure relatesparticularly to a novel top feed mechanism for an overedge sewingmachine of the type disclosed in US. Pat. No. 2,704,042, issued in thename of Ned L. Wallenberg et al. on Mar. 15, I959, and assigned to thepresent assignee. Machines of this type have been used for cord weltingslip covers, seaming pile linings with satin sleeves for the linings ofmen's raincoats, and similar multiply sewing operations.

Primary among the objects of the top feed mechanism of this inventionbeyond the adaptability thereof for the particular machine disclosed inthe latter-noted Wallenberg et al. patent is the simplicity ofconverting such overedge machines to include the top feed mechanism,simplicity of operation of the top feed mechanism, and the generalfoolproof operability thereof irrespective of the different types offabrics adapted to be sewn thereby.

The top feed mechanism includes a feed bar to which is imparted lift andfeed motions by appropriate eccentrics, a top feed dog, and meansarticulately mounting the top feed dog to the top feed bar to permit thefeed dog to automatically move away from an associated main feed dogwhen passing over a seam or other obstruction during a sewing operationwhile still achieving a feeding function in conjunction with the mainfeed dog.

A further object of this invention is to provide a novel top feedmechanism of the type described wherein means are provided for biasingthe top feed dog toward its fabric engaging position, and means foradjusting the biasing means to regulate the force applied to the fabricby the top feed dog during a sewing operation to adapt the top feedmechanism for sewing different types, thicknesses, etc., of fabric.

Yet another object of this invention is to provide a novel top feedmechanism of the type described wherein means are provided for cammingthe top feed dog away from its fabric engaging position simultaneouslywith the lifting of an associated presser foot to facilitate the removaland/or introduction of fabric relative to the feed mechanism.

Another object of this invention is to provide a novel top feedmechanism in which the top feed dog mounting means includes a pivotallymounted arm carrying the feed dog for pivotal movement relative to thetop feed bar, an actuator rod connected to the arm, and means for movingthe rod to pivot the arm and the feed dog carried thereby away from itsfabric engaging position, the last mentioned means being a cam rotatableagainst the rod to impart sliding movement to the latter and thus pivotthe top feed dog in a direction away from the main feed dog and itsassociated throat plate.

A further object of this invention is to provide a novel feed mechanismof the type described wherein the associated sewing machine includes amain feed bar carrying a main feed dog, and means are provided forimparting lift motion to the feed bars in the form of first and secondeccentric means, and the first and second eccentric means are generallyl80 out of phase with each other whereby the feed dogs move toward eachother to grip fabric therebetween during the feed cycle and move awayfrom each other to release fabric incident to the return cycle of themechanism.

Yet another object of this invention is to provide a novel feedmechanism of the type described including feed motion imparting meansfor moving the feed bars, the feed motion imparting means being definedby third and fourth eccentric means coupled to the main and top feedbars, and the eccentricities of the third and fourth eccentric meansbeing generally similar and in phase with each other whereby multiplyfabric pieces are fed evenly by the main and top feed dogs.

With the above and other objects in view that will hereinafter appear,the nature of the invention will be more clearly understood byreferenceto the following detailed description, the appended claimedsubject matter, and the several views illustrated in the accompanyingdrawings.

In the drawings:

FIG. 1 is an end elevational view of a sewing machine with portionsthereof broken away for clarity, and illustrates a top feed dog carriedby an arm pivotally mounted upon a support bracket of a top feed bar,and a spring biased cam operated actuating rod for moving the top feeddog away from the throat plate simultaneously with the lifting of anassociated presser plate.

FIG. 2 is a fragmentary vertical sectional view taken generally alongline 22 of FIG. 1, and illustrates two eccentric portions of acrankshaft for imparting lifting and feed motions to the top and mainfeed bars.

FIG. 3 is a fragmentary top perspective view of the machine lookingdownwardly in FIG. 1, and illustrates the general position of the topfeed mechanism above and in alignment with the top feed bar.

FIG. 4 is a fragmentary elevational view of the rear of the sewingmachine as viewed from left-to-right in FIG. 1, and illustrates atreadle operated link for rotating a plate having a cam surface forimparting motion to the actuator rod and pivoting the top feed dogsimultaneously with the lifting of the presser foot.

FIG. 5 is a sectional view taken generally along line 5-5 of FIG. 3, andmore clearly illustrates additional details of the top feed mechanism.

FIG. 6 is an enlarged fragmentary sectional view taken generally alongthe line 66 of FIG. 5 and more clearly illustrates the manner in whichthe top feed dog arm is articulately connected to the top feed bar andto the associated lifting rod.

FIG. 7 is an enlarged fragmentary sectional view taken generally alongline 77 of FIG. 5, and illustrates details of a mounting collar for theactuating rod.

Referring to the drawings in detail, the sewing machine (unnumbered)illustrated and most of the mechanisms thereof are similar to thatillustrated and described in the aforementioned patent to Wallenberg etal., and thus the present description will pertain only to the noveltop'feed mechanism therefor, and only so much of the machine and itscomponents as are necessary for a complete understanding of the top feedmechanism.

The sewing machine includes a frame 10 having a crankshaft l1 journaledin suitable bearings l2, 13 (FIG. 2), and similar suitable bearings (notshown) provided at the right (unillustrated) end of the frame 10, asviewed in FIG. 2. Also, within the machine frame 10, a and directlyabove the crankshaft 1 1, there is a needle driving shaft 14 journalednear its end (unnumbered) in a bearing 15. A bearing (not shown) is alsoprovided at the right end of the needle driving shaft, again as viewedin FIG. 2 though not illustrated therein.

The crankshaft 11 extends outwardly of the machine frame 10, and the endportion thereof projecting outwardly includes two eccentric portions 16,17 and a threaded terminal end 18. The eccentric portion 16 is the feedstroke eccentric and the eccentric portion 17 is the feed lifteccentric. The feed stroke eccentric 16 has a slightly largereccentricity than the feed lift eccentric 17, while the threadedterminal end 18 is concentric with the main portion (unnumbered) of thecrankshaft 11.

The feed lift eccentric portion 11 carries eccentric meansin the form ofa top feed lift eccentric l9 and a main feed lift block 20. The top feedlift eccentric 19 is secured by a screw (unnumbered) to the eccentricportion 17, while the main feed lift block is loose on the eccentricportion 17 allowing the eccentric portion 17 to rotate freely in themain feed lift block 20. A forked front portion 21 of a top feed bar 22surrounds the top feed lift eccentric 19. Adjacent the top feed bar 22and to the left thereof, as viewed in FIG. 2, is a main feed bar 23. Themain feed bar 23 similarly has a forked front portion 24 which surroundsthe main feed lift block 20. The two feed bars extend toward the rear ofthe machine frame 10, and at their rear ends are supported by guideblocks 25, 26 carried by an eccentric stud 27. The eccentric stud 27 issecured in an upstanding portion 28 of the machine frame 10. The guideblocks 25, 26 are received in forked portions 29, 30 at the rear end ofeach of the feed bars 22, 23, respectively.

The eccentric portion 16 of the crankshaft 11 carries two feed strokeeccentrics 31, 32 fixed in position upon the eccentric portion 16 by akey 33 (FIG. 2). The two feed stroke eccentrics 31, 32 are held on theeccentric portion 16 by a washer 34 and a nut 35 secured to the threadedend 18. The outermost feed stroke eccentric 31 drives the main feed bar23, and the inside feed stroke eccentric 32 drives the top feed bar 22.Drive means for the top feed bar 22 consists of a driving link or crank36 surrounding the feed stroke eccentric at its forward end(unnumbered), while the rear end (also unnumbered) of the link 36 isconnected to the top feed bar 22 by a feed driving stud 37 (FIG. 1) heldin place by a nut 38. Drive means for the main feed bar 23 consists of ashorter driving link or crank 39 surrounding the feed stroke eccentric31 (FIG. 1) at its forward end (unnumbered), while the rear end (alsounnumbered) of the link 39 is connected to the main feed bar 23 by afeed driving stud 40 which passes from the main feed bar 23 through aclearance hole 41 in the driving link 36 and is held fast upon thedriving link 39 by a nut 42.

A feed dog 43 is secured by a screw 44 to the main feed bar 23. The mainfeed bar and the feed dog 43 carried thereby operate in the mannerdescribed in the Wallenberg et al. patent, and a further descriptionthereof is considered unnecessary for a complete understanding of thisinvention.

The top feed bar 22 carries the top feed mechanism of this inventionincluding a feed dog carrier mounting bracket 45 secured by a screw 46in a slot (unnumbered) at the front end of the top feed bar 22. The topfeed dog carrier mounting bracket 45 extends upwardly and rearwardly, asviewed in FIG. I, and is provided with a threaded hole (unnumbered) atits upper end. A shoulder screw 47 cooperates with the threaded hole formounting a top feed dog carrier or arm 48 intermediate its ends upon thebracket 45. The top feed dog carrier 48 is thus pivotally mounted by thescrew 47 for movement from the position shown in FIG. 1 to a secondposition (not shown) in a counterclockwise direction. As shown in FIG.1, the arm 48 is disposed along with a top feed dog in the fabricfeeding position while when pivoted counterclockwise, the feed dog 50 islifted away from the fabric and the main feed dog 43 to prevent fabricfeed and permit either the introduction or removal of fabric between thefeeddogs 43, 50. The feed dog arm 48 includes a vertical slot 49 whichreceives an end (unnumbered) of the feed dog 50 which is secured in theslot 49 by a screw 51.

An opposite end of the feed dog arm 48 extends downwardly from the pivotpoint defined by the screw 47 and includes a bore 52 into which isreceived from the inside of the arm 48 a lifter rod 53. The rod is heldin position within the bore 52 by a snap ring 54. The rod 53 extendsparallel to and in alignment above the top feed bar 22. The rod 53passes through mounting means in the form of a guide bearing 55 mountedby screws 56 (FIG. 7) at the rear of the top feed bar 22. Locating means57, 59 in the form of collars are mounted on the rod 53 to the left andright, respectively, of the guide bearing 55. Biasing means in the formof a spring 58 is contained between the collar 57 and the guide bearing55 and functions to bias the rod 53 to the left as viewed in. FIG. 1thereby continually tending to pivot the arm 48 and the top feed dog 50carried thereby in a clockwise direction. The col-- lar 59 limitsthemovement of the rod 53 to the left, as also viewed in FIG. 1 of thedrawings. Therefore, the cooperation of the spring 58 pushing the rod 53to the left and the collar 59 holding the rod 53 in the position shownin FIG. 1 maintains the top feed dog 50 in a stationary positionrelative to the top feed bar 22 during the operation of the latter.However, the spring 58 will yield allowing the top feed dog 50 and thearm 48 to pivot about the axis of the screw 47 and thus rise whenpassing over a seam or other obstruction on the fabric during a sewingoperation. Also, the pressure applied by the top feed dog 50 upon thefabric can be varied by controlling the tension of the spring 58 simplyby relatively adjusting the collar 57 and locking the same at anyposition along the rod 53 by the illustrated though unnumbered setscrews. If, for example, the collar 57 is moved to the right as viewedin FIG. 1, the biasing force of the spring 58 is increases whileopposite movement results in a decrease of pressure applied by the topfeed dog 50 upon the fabric.

The sewing machine includes a presser foot lifting mechanism similar tothat illustrated and disclosed in the Wallenberg et al. patent, andoperates in substantially the same manner. However, to the existingmechanism there is added a top feed dog lifter plate 60 (FIG. 4)extending oppositely from the presser foot lifter lever 61. The lifterplate or lever 60 is mounted for pivotal movement on a shoulder screw62. An end (unnumbered) of the lever 60 is fixed to the lifter lever 61by a rod 70 passing through bores in both the plate 60 and the lever 61.The opposite end of the plate 60 extends upwardly and toward theterminal rear end of the lifter rod 53, as is best illustrated in FIGS.3 and 4. The end of the plate 60 is bent to form camming means in theform of a carnming surface 63.

As the presser foot lifter lever 61 is pulled down by a treadle or kneepress, the plate 60 will rotate in a counterclockwise direction, as isviewed in FIG. 4, and the camming surface 63 will progressively push therod 53 to the right, as viewed in FIG. 1, resulting in the lifting ofthe top feed dog 50 away from a throat plate 64 and the main feed dog 43in order to facilitate the insertion or removal of the fabric. At thesame time, the rod 70 being pulled down by the lifter lever 61 will inturn pull down a lever 65 having an end (unnumbered) connected to ashaft 66 causing the rotation of the latter in a counterclockwisedirection, as viewed in FIG. 1. The shaft 66 is connected by an arm 71to the presser foot 67 thereby resulting in the lifting of the presserfoot 67 away from the throat plate 64 simultaneously with a like liftingof the top feed dog 50.

Reference is now made particularly to FIGS. 2 and 5 wherein it will benoted that the top feed lift eccentric 19 has its eccentricitysubstantially 180 out of phase from that of the eccentric portion 17which is used for lifting the main feed bar 23. Thus the main feed dog23 and the top feed dog 22 will be operating opposite to each other suchthat as the main feed dog 23 is rising the top feed dog 22 will befalling to meet the main feed dog resulting in a clamping action forfeeding the plies of fabric evenly. Likewise, release of the fabric atthe end of the feed stroke will take place by the simultaneous movementof the main and top feed dogs away from each other.

The feed stroke eccentrics 31, 32 are of substantially the sameeccentricity'in order to feed the plies of fabric evenly. However, theeccentrics 31, 32 may be changed or replaced by larger or smallereccentrics in order to obtain a longer or shorter feed stroke.Furthermore, it is to be understood that the top feed dog 50 could be ofa shape other than that illustrated in the drawings and could, forexample, be longer in order to be closer to the rear of the presser foot67, or it could be wider to the right side, as viewed in FIG. 3, andcloser to the needle line, or it could include a groove or cutout toallow for piping on the fabric to operation.

As in the Wallenberg et al. patent, the machine further includes aneedle carrier 72 and a needle 74 which are oscillated by the needledriving shaft which is in turn driven from the main crankshaft 11 in amanner disclosed in the latter noted patent.

pass therethrough during a sewing While preferred forms and arrangementsof parts have been shown in illustrating the invention, it is to beclearly understood that various changes in details and arrangement ofparts may be made without departing from the spirit and scope of thisdisclosure.

I claim:

1. A top feed mechanism for sewing machines comprising a top feed barand a main feed bar, means articulately mounting a top feed dog uponsaid top feed bar, means mounting a main feed dog upon said main feedbar, first means for imparting lift and feed motions to said main feedbar, second means for imparting lift and feed motions to said top feedbar, lift imparting portions of said first and second means beingdirectionally in phase whereby said feed dogs move toward and away fromeach other in substantial unison during respective feed and retractcycles of said feed bars, and common drive means for imparting motion tosaid lift imparting portions.

2. The top feed mechanism as defined in claim 1 including means forbiasing said top feed dog toward its fabric engaging position.

3. The top feed mechanism as defined in claim 1 including means forbiasing said top feed dog toward its fabric engaging position, and meansfor adjusting said biasing means to regulate the force applied to fabricby said top feed dog.

4. The top feed mechanism as defined in claim 1 including means forcamming said top feed dog away from its fabric engaging position,

5. The top feed mechanism as defined in claim 1 including means forlimiting the movement of said top feed dog between fabric engaging andfabric disengaging positions thereof.

6. The top feed mechanism as defined in claim 1 wherein said mountingmeans includes means for pivotal movement of said top feed dog relativeto said feed bar.

7. The top feed mechanism as defined in claim 1 wherein said mountingmeans includes a pivotally mounted arm carryin g said top feed dog forpivotal movement relative to said top feed bar, an actuator rodconnected to said arm, and means for moving said rod to pivot said armand the top feed dog carried thereby away from its fabric engagingposition.

8. The top feed mechanism as defined in claim 7 including means carriedby said top feed bar mounting said rod for sliding movement relativethereto.

9. A top feed mechanism comprising a top feed bar adapted to be mountedbelow the horizontal plane of an associated sewing machine throat plate,means for imparting lift and feed motions to said top feed bar, a feeddog, means articulately mounting said feed dog upon said top feed bar,said mounting means including a pivotally mounted arm carrying said feeddog for pivotal movement relative to said feed bar, an actuator rodconnected to said arm, means for moving said rod to pivot said arm andthe feed dog carried thereby away from its fabric engaging position,means carried by said feed bar mounting said rod for sliding movementrelative thereto, and said rod moving means includes cam means forimparting sliding movement to said rod.

10. The top feed mechanism as defined in claim 9 including means forrotating said cam means incident to imparting sliding movement to saidrod.

11. A top feed mechanism comprising a top feed bar adapted to be mountedbelow the horizontal plane of an associated sewing machine throat plate,means for imparting lift and feed motions to said top feed bar, a feeddog, means articulately mounting said feed dog upon said top feed bar,said mounting means including a pivotally mounted arm carrying said feeddog for pivotal movement relative to said feed bar, an actuator rodconnected to said arm, means for moving said rod to pivot said arm andthe feed dog carried thereby away from its fabric engaging position,means carried by said feed bar mounting said rod for sliding movementrelative thereto, means carried by said rod and cooperative with saidrod mounting means for limiting the movement of said rod in a firstdirection, and means for biasing said rod for movement in said firstdirection.

12. A feed mechanism for a sewing machine comprising a main feed bar anda top feed bar carrying respective main and top feed dogs, means forimparting feed motion to said feed bars, means for imparting lift motionto said feed bars, said lift motion imparting means being defined byfirst and second eccentric means coupled to said main and top feed barsrespectively, one of said lift motion imparting eccentric means beingcarried by and surrounding the other of said lift motion impartingeccentric means, and said first and second eccentric means beinggenerally out of phase with each other whereby said feed dogs movetoward each other to grip fabric therebetween during the feed cycle andmove away from each other to release fabric incident to the returncycle.

13. The feed mechanism as defined in claim 12 including a rotatableshaft, and said first and second eccentric means are commonly actuatedby said rotatable shaft.

14. The feed mechanism as defined in claim 13 wherein at least one ofsaid first and second eccentric means is fixedly secured to saidrotatable shaft.

15. The feed mechanism as defined in claim 12 wherein said feed motionimparting means is defined by third and fourth eccentric means coupledto said main and top feed bars respectively, and the eccentricities ofsaid third and fourth eccentric means being generally similar and inphase with each other whereby multiply fabric pieces are fed evenly bysaid main and top feed dogs.

16. The feed mechanism as defined in claim 15 including a rotatableshaft having an eccentric portion, and said third and fourth eccentricmeans are commonly actuated by said eccentric portion.

17. A feed mechanism for a sewing machine comprising a main feed bar anda top feed bar carrying respective main and top feed dogs, means forimparting feed motion to said feed bars, means for imparting lift motionto said feed bars, said lift motion imparting means being defined byfirst and second eccentric means coupled to said main and top feed barsrespectively, said first and second eccentric means being generally 180degrees out of phase with each other whereby said feed dogs move towardeach other to grip fabric therebetween during the feed cycle and moveaway from each other to release fabric incident to the return cycle,said feed motion imparting means is defined by third and fourtheccentric means coupled to said main and top feed bars respectively, theeccentricities of said third and fourth eccentric means being generallysimilar and in phase with each other whereby multiply fabric pieces arefed evenly by said main and top feed dogs, rotatable shaft having aneccentric portion, and said third and fourth eccentric means arecommonly actuated by said eccentric portion, said rotatable shaftincludes another eccentric portion, and said first and second eccentricmeans are commonly actuated by said last-mentioned eccentric portion.

18. The top feed mechanism as defined in claim 1 wherein said top feedbar and said articulate mounting means are disposed below the plane ofengagement of said top and main feed dogs.

1. A top feed mechanism for sewing machines comprising a top feed barand a main feed bar, means articulately mounting a top feed dog uponsaid top feed bar, means mounting a main feed dog upon said main feedbar, first means for imparting lift and feed motions to said main feedbar, second means for imparting lift and feed motions to said top feedbar, lift imparting portions of said first and second means beingdirectionally in phase whereby said feed dogs move toward and away fromeach other in substantial unison during respective feed and retractcycles of said feed bars, and common drive means for imparting motion tosaid lift imparting portions.
 2. The top feed mechanism as defined inclaim 1 including means for biasing said top feed dog toward its fabricengaging position.
 3. The top feed mechanism as defined in claim 1including means for biasing said top feed dog toward its fabric engagingposition, and means for adjusting said biasing means to regulate theforce applied to fabric by said top feed dog.
 4. The top feed mechanismas defined in claim 1 including means for camming said top feed doG awayfrom its fabric engaging position.
 5. The top feed mechanism as definedin claim 1 including means for limiting the movement of said top feeddog between fabric engaging and fabric disengaging positions thereof. 6.The top feed mechanism as defined in claim 1 wherein said mounting meansincludes means for pivotal movement of said top feed dog relative tosaid feed bar.
 7. The top feed mechanism as defined in claim 1 whereinsaid mounting means includes a pivotally mounted arm carrying said topfeed dog for pivotal movement relative to said top feed bar, an actuatorrod connected to said arm, and means for moving said rod to pivot saidarm and the top feed dog carried thereby away from its fabric engagingposition.
 8. The top feed mechanism as defined in claim 7 includingmeans carried by said top feed bar mounting said rod for slidingmovement relative thereto.
 9. A top feed mechanism comprising a top feedbar adapted to be mounted below the horizontal plane of an associatedsewing machine throat plate, means for imparting lift and feed motionsto said top feed bar, a feed dog, means articulately mounting said feeddog upon said top feed bar, said mounting means including a pivotallymounted arm carrying said feed dog for pivotal movement relative to saidfeed bar, an actuator rod connected to said arm, means for moving saidrod to pivot said arm and the feed dog carried thereby away from itsfabric engaging position, means carried by said feed bar mounting saidrod for sliding movement relative thereto, and said rod moving meansincludes cam means for imparting sliding movement to said rod.
 10. Thetop feed mechanism as defined in claim 9 including means for rotatingsaid cam means incident to imparting sliding movement to said rod.
 11. Atop feed mechanism comprising a top feed bar adapted to be mounted belowthe horizontal plane of an associated sewing machine throat plate, meansfor imparting lift and feed motions to said top feed bar, a feed dog,means articulately mounting said feed dog upon said top feed bar, saidmounting means including a pivotally mounted arm carrying said feed dogfor pivotal movement relative to said feed bar, an actuator rodconnected to said arm, means for moving said rod to pivot said arm andthe feed dog carried thereby away from its fabric engaging position,means carried by said feed bar mounting said rod for sliding movementrelative thereto, means carried by said rod and cooperative with saidrod mounting means for limiting the movement of said rod in a firstdirection, and means for biasing said rod for movement in said firstdirection.
 12. A feed mechanism for a sewing machine comprising a mainfeed bar and a top feed bar carrying respective main and top feed dogs,means for imparting feed motion to said feed bars, means for impartinglift motion to said feed bars, said lift motion imparting means beingdefined by first and second eccentric means coupled to said main and topfeed bars respectively, one of said lift motion imparting eccentricmeans being carried by and surrounding the other of said lift motionimparting eccentric means, and said first and second eccentric meansbeing generally 180* out of phase with each other whereby said feed dogsmove toward each other to grip fabric therebetween during the feed cycleand move away from each other to release fabric incident to the returncycle.
 13. The feed mechanism as defined in claim 12 including arotatable shaft, and said first and second eccentric means are commonlyactuated by said rotatable shaft.
 14. The feed mechanism as defined inclaim 13 wherein at least one of said first and second eccentric meansis fixedly secured to said rotatable shaft.
 15. The feed mechanism asdefined in claim 12 wherein said feed motion imparting means is definedby third and fourth eccentric means coupled to said main and top feedbars respectively, and the eccentricities of said third and fourtheccentric means being generally similar and in phase with each otherwhereby multiply fabric pieces are fed evenly by said main and top feeddogs.
 16. The feed mechanism as defined in claim 15 including arotatable shaft having an eccentric portion, and said third and fourtheccentric means are commonly actuated by said eccentric portion.
 17. Afeed mechanism for a sewing machine comprising a main feed bar and a topfeed bar carrying respective main and top feed dogs, means for impartingfeed motion to said feed bars, means for imparting lift motion to saidfeed bars, said lift motion imparting means being defined by first andsecond eccentric means coupled to said main and top feed barsrespectively, said first and second eccentric means being generally 180degrees out of phase with each other whereby said feed dogs move towardeach other to grip fabric therebetween during the feed cycle and moveaway from each other to release fabric incident to the return cycle,said feed motion imparting means is defined by third and fourtheccentric means coupled to said main and top feed bars respectively, theeccentricities of said third and fourth eccentric means being generallysimilar and in phase with each other whereby multiply fabric pieces arefed evenly by said main and top feed dogs, rotatable shaft having aneccentric portion, and said third and fourth eccentric means arecommonly actuated by said eccentric portion, said rotatable shaftincludes another eccentric portion, and said first and second eccentricmeans are commonly actuated by said last-mentioned eccentric portion.18. The top feed mechanism as defined in claim 1 wherein said top feedbar and said articulate mounting means are disposed below the plane ofengagement of said top and main feed dogs.